1. Field of the Invention.
This invention relates in general to jigs used to support drills, reamers and like tools and, more particularly, to drill jigs useful in on-site marine engine and gear box hole drilling and reaming.
2. Prior Art.
A long time outstanding problem in the marine industry has been the oblong and mislocated (e.g., off centerline) bolt holes found in marine engine foundations. This out-of-perpendicular orientation of the bolt holes causes the engine mount bolts to seat improperly and/or allow the bolt to shift within the opening. As a result, engine bolts become loosened, resulting in bolt failure due to bending as well as engine to clutch misalignment. These result in overstress of the transmission and cutless bearing leading to expensive and unnecessary maintenance costs.
Current apparatus and methods do not permit on-site bolt hole drilling and reaming accuracy necessary to produce true body bound engine mount bolt installation as called for by engine and clutch-transmission manufacturers. For example, magnetic base drills do not provide adequate support force to prevent drill bit moving laterally off-center when heavy side loads are induced by bits and reamers. Likewise, vacuum base drills cannot be utilized since engine mount brackets and transmission mount flanges are irregular shaped generally near the fillet radii of vertical flanges, thereby not providing sufficient space for adequate air sealing required by the vacuum base. Furthermore, current drill jigs utilized for drilling holes near edge of metal sheets are not satisfactory since they are designed to guide the drill rather than the drill bit and will not accommodate the tang of tapered shank drills and reamers. In addition, current drill bushings are not practical because the drilling forces utilized in this application would induce heavy side loads causing such bushings to shift laterally. Finally, dowel pin jigs, pipe taping, as well as current portable or fixed drill presses and lathes have not been able to produce the required accuracy or be adaptable for use for drilling engine and/or transmission mount bolt holes.
Exemplary of the current apparatus and methods are the disclosures described in the following patents:
__________________________________________________________________________ Patent No. Inventor Issue Date Title __________________________________________________________________________ 3,552,238 Quackenbush 01/05/71 STRUCTURE FOR POSITIVELY FEEDING TOOLS SUCH AS DRILLS AND THE LIKE 3,552,239 Yeaman, et al 01/05/71 PORTABLE DRILL PRESS 3,587,391 Pitts, et al 06/28/71 WORK SUPPORT MECHANISM 3,626,513 Pytlak 12/07/71 TOOL GUIDE 3,677,655 Ratteree 07/18/72 BRAKE DRUM TRUING METHOD AND APPARATUS 3,677,656 Buck 07/18/72 RADIAL POSITIONER, LOCK AND ROTARY CONTACTS FOR ELECTRO- MAGNETIC DRILL MOUNT 3,685,916 Loomis 08/22/72 BOLT HOLE DRILLING JIG FOR ELEVATOR INSTALLATION 3,751,175 Brooks 08/07/73 PORTABLE LINE BORING BAR ASSEMBLY 3,756,736 Marcoux 09/04/73 DRILL BUSHING SYSTEM 3,758,933 Gross 09/18/73 PRESSURE FOOT GUIDE DEVICE 3,833,313 Gallion 09/03/74 DRILLING DEVICE 3,851,990 West 12/03/74 DISPOSABLE DRILL GUIDE AND METHOD FOR DRILLING WORKPIECES 3,922,107 Fowler 11/25/75 SEWER TAPPING METHOD AND APPARATUS 3,992,122 Maxey 11/16/76 HIGH VELOCITY 4,005,945 Gutman 02/01/77 DRILL GUIDE 4,105,358 Walker 08/08/78 SUPPORT DEVICE FOR PIPE DRILLER 4,132,496 Casto 01/02/79 PRECISE ANGLE DRILLING ATTACHMENT 4,197,041 Prewitt 04/08/80 BORING TOOL __________________________________________________________________________